Reasons for Infertility

Approximately one in six couples has difficulty achieving a pregnancy.

Research suggests that infertility problems can be attributed to:

  • female factors in 30% of cases
  • male factors in 30% of cases
  • combined male and female factors in 20% of cases
  • unexplained factors in 20% of cases.

Under normal circumstances, the chances of pregnancy occurring as a result of unprotected intercourse during the fertile time of the cycle are about 10-12% per month only in young couples. After 12 months of trying, approximately 77% of couples will have conceived.

For women between 35 and 38, approximately 66% would have conceived within the first year and the pregnancy rate per month would be approximately 8-9%.

For women over 38 the chances of pregnancy occurring as a result of unprotected intercourse during the fertile time of the cycle are about 5-7%. After 12 months of trying, approximately 45% of women over 38 will have conceived.

Female infertility

A woman usually produces a single egg follicle in the ovaries each month and once this egg is mature, it is released. The fallopian tube moves it towards the uterus for fertilisation.

Common female infertility problems include:

  • ovulatory problems including polycystic ovaries.
  • tubal blockage.
  • endometriosis.
  • fibroids and other abnormalities of the uterus.
  • age-related changes in egg quality.

Ovulatory problems

The most common cause of female infertility, ovulatory problems occur as a result of hormonal imbalances which may be caused through stress, weight loss or gain, excessive prolactin production (the hormone that stimulates milk production in the breasts) and polycystic ovarian disease.

Polycystic ovaries

About 20% of women have polycystic ovaries (PCO), which appear as an increased number of small egg follicles under the surface of the ovary. Many women with PCO have normal regular cycles and don’t have problems conceiving.

However, some women may have polycystic ovarian syndrome (PCOS), which may lead to a hormone imbalance with irregular or absent periods. They may have difficulty conceiving because they are not ovulating regularly.

PCOS is treated with drugs to correct the hormone imbalance and to stimulate ovulation. Laparoscopic ovarian drilling (making tiny holes on the surface of the ovaries using diathermy or laser) may be performed. In cases of PCOS these two modes of treatment may precede an IVF treatment cycle.

Tubal blockage

Normally the fallopian tubes act like fishing rods, picking up the released egg and helping to move it towards the uterus, except when these tubes have been damaged – then they may not effectively transport the egg and subsequently prevent fertilisation.

If fluid collects in the fallopian tube (hydrosalpinx), it may be a potential source of chronic infection and it’s recommended that a hydrosalpinx is removed before IVF treatment.

Some blockages can be treated by laparoscopic surgery or micro-surgical techniques, but in other cases pregnancy can only be achieved with IVF.


Endometriosis arises when tissue which normally lines the womb, is found at other sites in the pelvis. At the time of menstruation, bleeding occurs from this tissue and this may give rise to abdominal pain and painful intercourse. Blood-filled cysts may also develop within the ovaries. It is suggested that endometriosis reduces the ability of the fallopian tube to pick up the eggs.

Laparoscopic treatment of endometriosis using a diathermy or a laser may improve the fertility of the patient. IVF is an appropriate treatment for infertility associated with endometriosis where other methods have failed and any resulting pregnancy is usually an excellent temporary cure for endometriosis.


Fibroids are common and grow in the muscle wall of the uterus. They are benign fibrous tissue and can vary in size from a few millimetres to several centimetres. They may be single or multiple and can enlarge the uterus. Fibroids that grow into the uterine cavity under the endometrial lining reduce the chances of an embryo implanting but they can be removed surgically.

Age related change in ovarian reserve and egg quality
Unlike men, who can generate new sperm throughout life, women are born with all the eggs they will ever have in their ovaries. From birth the number of eggs remaining in the ovaries declines steadily until a woman’s late 30’s early 40’s when the loss accelerates. When the reserve of eggs is depleted a woman goes through the menopause.

In addition to the reduction in numbers of eggs in the ovaries (reduced ovarian reserve) the quality of eggs also deteriorates with age. Eggs become more susceptible to being genetically abnormal and when those eggs fertilise the resulting embryo is less likely to develop normally to implantation and more likely to miscarry. As women leave starting a family until later than in the past, this age-related decline in reserve and quality of eggs is a significant cause of delayed conception. These changes also reduce the chances of fertility treatment such as IUI and IVF being successful in women in their 40’s.

Male infertility problems

Causes of male infertility can be divided into two categories:

1) physical abnormalities of the male reproductive tract, such as epididymal or vas obstruction or impaired sperm production.

2) abnormalities of the sperm themselves.

However, in most cases of male infertility the cause is unknown.

To determine male fertility we carry out a semen analysis which tests the number, activity and shape of the sperm. A normal assessment should show a sperm count of more than 20 million sperm per millilitre with at least 50% of the sperm actively moving and more than 30% of the sperm of normal shape. They must be capable of moving through the female genital tract to reach the fallopian tube where the egg is fertilised, and so must survive for a period of 24-48 hours.

Common male infertility problems are due to the following:

  • Abnormal sperm parameters.
  • Azoospermia (no sperm in the ejaculate).
  • Antisperm antibodies.


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